Condition responsive snap-action electrical switch



Oct. 5, 1965 s. H. SCHWARTZ I 3,210,497

CONDITION RESPONSIVE SNAP-AGTION ELECTRICAL SWITCH Filed Nov. 6, 1962 INVENTOR.

5AMUEL. H- 5CHWA|ZTZ ATTO 12 N 5Y6 United States Patent 3,210,497 CONDITION RESPONSIVE SNAP-ACTION ELECTRICAL SWITCH Samuel H. Schwartz, Deerfield, Ill., assignor to The Dole Valve Company, Morton Grove, 111., a corporation of Illinois Filed Nov. 6, 1962, Ser. No. 235,672 2 Claims. (Cl. 20067) This invention relates to improvements in snap-acting switches.

A principal object of the invention is to improve upon the snap-acting switches heretofore in use by providing a one piece switch in which the switch snap blade and overcenter spring are of an integral structure.

A further object of the invention is to provide a onepiece snap-acting switch arranged with a view toward utmost simplicity in construction and efiiciency in operation.

Another object of the invention is to provide a novel and improved form of snap-acting switch in which the switch blade has an open central portion having an integrally formed switch arm extending therealong and in which the overcenter spring forms a backwardly looped continuation of the snap blade and extends within the open portion of the snap blade and has a switch arm connected thereto.

These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawing wherein:

FIGURE 1 is a top plan view of a snap-acting switch constructed in accordance with the principles of the present invention with the cover for the switch casing removed; and

FIGURE 2 is a vertical sectional view taken through the switch casing substantially along line IIII of FIG- URE 1.

In the embodiment of the invention illustrated in FIG- URES 1 and 2 of the drawings, I have shown a switch casing having a bottom wall 11, a top cover 12 and side and end walls 13 and 14, respectively. The bottom wall 11 has a generally cylindrical recessed portion 15 depending therefrom and forming a receptacle for a thermally responsive element 16.

As shown in FIGURE 2, the thermally responsive element 16 is a well known form of power or high motion type of thermally responsive element in which a fusible thermally expansible material contained with a casing 17 for the thermally expansible element, acts against a diaphragm (not shown) clamped within said casing by a clamping ring 18, to extend a piston or power member 19 with respect to the casing 17 upon increases in temperature sufficient to effect fusion of the fusible thermally expansible material contained within the casing 17, as shown and described in Patent No. 2,368,181 which issued to Sergius Vernet on January 30, 1945, and no part of the present invention, so not herein shown or described further. It should, of course, be understood that the thermally responsive element 16 is shown for illustrative purposes only, and other types of thermally responsive elements may be substituted for the element 16, and a pressure operated operator may be used to operate the switch, if desired.

As shown in FIGURE 2, the clamping ring 18 fits within the wall of the cylindrical recessed portion 15 and abuts an integrally extending radial flanged portion 20 of said recessed portion, which forms a stationary reaction member for the thermally responsive element.

The power member or piston 19 abuts the underside of a resilient blade 21, adjacent the free end thereof. The resilient blade 21 may be made from a spring material 3,216,497 Patented Oct. 5, 1965 such as Phosphor bronze or any other desired spring material, which also forms a good electrical conductor and has a fixed end 23 abutting the top surface of a block 24, which may be made from an insulating material. The fixed end 23 of the resilient blade 21 is clamped to the block 24 by a clamping block 25 and machine screws 26, which may be threaded within the bottom wall 11 of the casing 10.

A contact member 29 has a base portion 30 shown as extending along the fixed end 23 of the resilient blade 21 and as turned at right angles to said resilient blade along the outer side of the clamping block 25 and through the cover 12, to form a contact means which may make contact within a suitable electrical receptacle (not shown).

The resilient blade 21 is shown in FIGURE 1 as being generally rectangular in plan view and as having a cut away central portion 31, generally U-shaped in plan, the inner margins of the legs of which are formed by a switch arm 32 extending from the fixed end 23 of the resilient blade 21 along the center of said cut away portion and formed integrally with said resilient blade. The switch arm 32 has a tongue 33 extending longitudinally from the free end thereof within an apertured portion of a depending end portion 35 of an overcenter spring 36. The overcenter spring 36 is shown as being formed integrally with and extending outwardly from the free end of the resilient blade 21 and as being narrower than said resilient blade and extending outwardly of the central portion of the free end of said resilient blade.

The overcenter spring 36 is turned backwardly from the free end of the resilient blade 21 over said blade and downwardly with respect to said blade to position the depending end 35 of said overcenter spring within the cut away portion 31 of said resilient blade, to accommodate the power member 19 to move said resilient blade past the point of connection of the switch arm 32 to said overcenter spring.

A means is provided to hold the switch blade 32 relatively stationary and accommodate the piston 19 of the thermally responsive element 16 to move the resilient blade past the point of connection of the switch arm 32 to said overcenter spring, which is herein shown as being a fixed abutment 37 which may be made from a material of high electrical conductivity and has a contact end portion 39 engaging a contact 40 brazed or otherwise secured to the top surface of the switch blade 32. The abutment 37 thus forms a stationary contact for the snap-acting switch and is mounted on the undersurface of a bridge 41 extending across the casing 10. The bridge 41 is shown as having right angled upwardly extending end portions 42, abutting the insides of the side walls 13 of the casing 10, and secured thereto by machine screws 43. A contact tongue 45 extends along the undersurface of the bridge 41 and is abutted by the fixed abutment 37. The contact tongue 45 extends parallel to the walls 13 outwardly through the cover 12 for the switch casing in alignment with the contact tongue 29, to be plugged into an electrical receptacle (not shown), which may be the same receptacle into which the contact tongue 29 is plugged.

The casing 17 of the thermally responsive element 16 may be positioned in heat sensing relation with respect to a source of heat, and as the fusible thermally responsive material contained within the casing 17 fuses, the power member 19 will be extended with respect to the easing 17 and move the resilient blade 21 past the point of connection of the switch arm 32 to the overcenter spring 36. As the resilient blade 21 moves past the point of connection of the switch arm 32 to the overcenter spring 36, the overcenter reaction between the overcenter spring 36 and switch arm 32 will snap the contact 40 out of engagement with the under contact surface 39 of the fixed abutment 37. As, however, the thermally responsive element 16 cools down, the resiliency of the snap blade 21 will return the power element 19 with respect to the casing 17 and efiect the snap engagement of the cont-act 40 with the contact surface 39, as the resilient blade moves past the point of connection of the switch arm 32 to the overcenter spring 36.

It may be seen from the foregoing that an extremely simple and effective snap-acting switch has been provided in which the resilient blade, switch arm and overcenter spring are made from one piece of material, and in which the switch contacts are opened and closed with a snap action as the resilient blade moves past the point of connection of the switch arm 32 to the overcenter spring 35 in either direction of travel of said resilient blade.

It may further be seen that the resilient blade 21 besides serving as a snap blade in cooperation with the overcenter spring 36 to snap the switch contacts to open and closed positions also serves as a return spring for the power member 19 of the thermally responsive element 16.

While I have herein shown and described one form in which my invention may be attained, it should be understood that the structure disclosed may be modified and varied in various ways without departing from the spirit and scope of the invention as defined by the claims appended hereto.

I claim as my invention:

1. In a snap-action switch,

a flat resilient blade supported at one end and having an opposite movable end,

movable about said one end in an arcuate direction generally perpendicular to the plane of said resilient blade,

said blade having a central elongated aperture extending from said one end to a position adjacent the movable end thereof,

a switch arm integral with said resilient blade and extending from said one end into said aperture along said blade toward the movable end of said aperture,

said flat blade having a spring portion integral with the movable end thereof and extending from said free end toward the free end of said switch arm as a loop,

and a rockable attaching connection between the free end of said switch arm and said spring portion; said blade, said switch arm,

.and said spring portion comprising a single piece;

whereby movement of said resilient blade past the point of rockable attaching connection between said switch arm and said blade effects snapping movement of said switch arm in a contact breaking direction.

2'. In a snap-action switch,

an elongated flat resilient blade having a fixed end and a free end movable about said fixed end in an arcuate path generally perpendicular to the plane of said blade,

said blade having an elongated aperture extending from said fixed end toward said free end,

an integral switch arm extending into and along said aperture toward the free end of said blade and having a free end movable relatively to the plane of said blade,

a stationary abutment on one side of said blade and limiting movement of said switch arm in a contact closing direction,

an actuator on the opposite side of said blade engaging said blade toward the free end thereof and moving said blade toward said abutment and returned by the stored up energy in said blade,

and means formed integrally with said blade for snapping said switch arm out of engagement with said abutment upon movement of said actuator and blade toward said abutment comprising,

a fiat spring forming a continuation of the free end of said blade and turned in the form of a loop toward the free end of said switch arm and having a free end portion movable into said elongated aperture,

and a rockable attaching connection between the free end of said switch arm and the end portion of said spring,

said blade, said switch arm, and said spring portion comprising a single piece.

References Cited by the Examiner UNITED STATES PATENTS 2,603,727 7/52 Auer 200--67 2,700,079 1/55 Haydon 200-67 2,840,669 6/58 Russell 200- 2,896,041 7/59 Schwaneke 200-67 X 2,949,132 8/60 Asakawa et al. 200-140 2,990,716 7/61 Butts.

BERNARD A. GILHEANY, Primary Examiner. 

1. IN A SNAP-ACTION SWITCH, A FLAT RESILIENT BLADE SUPPORTED AT ONE END AND HAVING AN OPPOSITE MOVABLE END, MOVABLE ABOUT SAID ONE END IN AN ARCUATE DIRECTION GENERALLY PERPENDICULAR TO THE PLANE OF SAID RESILIENT BLADE, SAID BLADE HAVING A CENTRAL ELONGATED APERTURE EXTENDING FROM AID ONE END TO A POSITION ADJACENT THE MOVABLE END THEREOF, A SWITCH ARM INTEGRAL WITH SAID RESILIENT BLADE AND EXTENDING FROM SAID ONE INTO SAID APERTURE ALONG SAID BLADE TOWARD THE MOVABLE END OF SAID APERTURE, SAID FLAT BLADE HAVING A SPRING PORTION INTEGRAL WITH THE MOVABLE END THEREOF AND EXTENDING FROM SAID FREE END TOWARD THE FREE END OF SAID SWITCH ARM AS A LOOP, AND A ROCKABLE ATTACHING CONNECTION BETWEEN THE FREE END OF SAID SWITCH ARM AND SAID SPRING PORTION; SAID BLADE, SAID SWITCH ARM, 